Gonzalez was having a good game, as he started the game with a leadoff homerun in the first inning, but apparently reinjured the wrist that was bruised on the road trip before the All Star Break. Instead of going onto the Disabled List to completely heal, Gonzalez has been taking cortisone shots to relieve some pain.
While it's not certain what exactly happened (it doesn't appear that he struck the wrist with the bat), pain during the middle of a swing and with a previous injury is not a good sign for Gonzalez's health going forward. If he's injured for a lengthy period of time, the Rockies' slim chances of making a run at the playoffs become very slim.
If Gonzalez does go onto the 15 day DL, AAA outfielder Cole Garner could make his third appearance in the majors this season. Another alternative is top prospect Tim Wheeler, who is enjoying a breakout season with the AA Tulsa Drillers and was already a favorite for a September callup.